Granted Patent
Utility
US 4,894,448 · App. 07/271,347
Process for the preparation of low-viscosity cellulose ethers
Inventor:
Heinz Pelzer
Patented Case
View Patent ↗
Granted: Jan 16, 1990
Filed: Nov 14, 1988
Inventor
Heinz Pelzer
Assignee (at issue)
Hoechst GmbH
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.